“[T]he data suggest that the secular trajectories of low homicide rates differ among large geographic areas. It appears that English homicide rates were already considerably lower in the late sixteenth century than during the late Middle Ages and that they declined continuously along a log-linear trend over several centuries. Extant estimates for the Netherlands and Belgium suggest a very similar structure trend in these areas. In the Scandinavian countries, the transistion to the decreasing trend occurs notably later, namely in the first decades after 1600. Despite huge gaps in the data, the German-speaking areas may also be assumed to have joined the declining trend from the early seventeenth century onwards. For Italy, however, all the available data indicate that acts of individual-level lethal violence remained very frequent until the early nineteenth century. It is not until the mid-nineteenth century that the rate begins to decline, but then very steeply.”

“In the thirteenth and fourteenth century, the mean of almost 40 different estimates lies around 24 homicides per 100,000. The average homicide rates are higher for the late fourteenth century than for the thirteenth century, but it seems impossible to say whether this is due to the difference of the sources used or reflects a real increase related to the social and economic crises in the late Middle Ages. When estimate start again after a gap of some 150 years, the average calculated homicide rates are considerably lower with typical values of between 3-9 per 100,000. From then onwards, the data for Kent line up with surprising precision along a straight line that implies a long-term declining trend for more than 350 years.” [pg. 622]

begium/netherlands

“When plotted on a graph, the respective secular trends are very similar to those found for England. During the fourteenth and early fifteenth centuries, counts of murder and manslaughter cases in cities like Antwerp, Leuwen, Utrecht or Amsterdam consistently result in estimated homicide rates of between 30 and 60 cases per 100,000. Spierenburg presents a series of estimates for Amsterdam between the sixteenth and the early nineteenth centuries based on autopsy reports. He finds somewhat lower levels of about 20 per 100,000 in sixteenth-century Amsterdam…. Seventeenth-century homicide rates in both Amsterdam and Brussels are considerably lower and range between four and 11 per 100,000.” [pg. 623]

germany/switzerland

“In total, I found more than 30 estimates referring to various cities in the thirteenth and fourteenth century. They range between approximately eight and 80 homicides per 100,000, with an overall mean of 35…. Schwerhoff and Eibach present homicide rates based on convictions in the city of Francfourt am Main between the sixteenth and the late eighteenth centuries. A cluster of estimates around 1600 yields an average homicide rate of about 10 per 100,000.” [pg. 625]

scandinavia

“[The figure] suggests first that homicide rates typically ranged from 10 to 60 cases per 100,000 between the mid-fifteenth and the mid-seventeenth centuries and that the average rate may have been at about 25. Strikingly, the Scandinavian evidence shows no sign of declining homicide rates until about 1600. Yet by 1740, when the first Swedish national vital statistics are available, homicide rates are already below 1 per 100,000. The data thus suggest a spectacular decline of lethal personal violence by a factor of at least 10:1 within a period of only 150 years.” [pg. 624]

“The secular pattern in Italy … diverges decisively from the trend found for norther Europe. There exist isolated estimates for a number of Italian cities, such as Bologna, Florence, Mantova and Venice, whereby Florence shows the absolute highest homicide rate with 150 homicides per population of 100,000 in the fourteenth century. Blastenbrei provides homicide rates of 30 to 80 per 100,000 for Rome in the sixteenth century…. [T]he exant estimates do indicate that for a long period between the high Middle Ages and the seventeenth century in Italy, there was a slight decline in the frequency of homicides. However, Italy may be a particularly problematic case because of the vast differences between different areas. For example, Doneddu gives a homicide rate of 22 for late eighteenth-century Sardegna, while the data presented by Sardi for the duchy of Tuscany yield a rate of 4-5 per 100,000. Starting from 1881 … [t]he rate begins at about 8 per 100,000 and then — with the exception of higher rates during the final years of both world wars — falls steeply up to the mid 1960s.” [pgs. 626-27]

furthermore: “Durkheim showed that in the late nineteenth century an arc of high murder rates ranging from Ireland over Spain, Italy, Austria, and Hungary encircled a zone of low homicide rates.” [pg. 631]
_____

eisner comes a hair’s breadth away from a good sociobiological explanation for why all of this happened, but he missed it (prolly ’cause he’s a criminologist and not a biologist — not that there’s anything wrong with that!):

“[T]he work of Norbert Elias probably forms the most prominent theoretical framework discussed by those historians of crime who are interested in explaining this long-term trend. Elias’s well-known theoretical model of the ‘civilizing process’ embraces long-term social dynamics at a macro level as well as changes in typical psychological traits and the developments in characteristic modes of behaviour. In a nutshell, the theory of the civilizing process holds that over a period of several centuries a type of personality has come to prevail that is characterized by increasing affect control, decreasing impulsivity, and a rationalized manner of living — in brief: high levels of self-control. Higher levels of self-control imply, in turn, the gradual pacification of everyday interactions, which becomes manifest by lower levels of violent behaviour…. [pg. 619]

all of these traits, like impulse control (deferred gratification), are undoubtedly at least partly rooted in our natures. i think it’s likely that what happened over time in europe (and elsewhere?) is that greater impulse control, etc., etc., was selected for in the population — but i’m a reductionist (hey, i’m in good company!), so you knew i’d say that. (~_^)

eisner offers up one of the standard explanations for the decrease of violence over time and that’s the role of the state. the state took over as the executor of revenge (we call it justice now) so individuals/families no longer had to mete it out — AND the state really, really discouraged violence in general — if you were violent, you’d go to jail or maybe be executed. i think the idea that the state has played a big role in the reduction of violence over time makes a lot sense, ’cause these things that the state started doing sure sound like selection pressures — clearly the second one is especially if you execute violent criminals. you just take them and all their personality traits right out of the gene pool, no?

but eisner also mentions an idea of émile durkheim‘s related to the reduction of violence that’s right up my alley:

“Durkheim saw the decline of homicide rates as resulting from the liberation of the individual from collective bonds rather than as the consequence of the coercive potential of the state. High levels of lethal violence thus mirror the intensity of ‘collective emotions’, which bind the individuals to ‘groups of things that symbolically represent these groups’. Violence thus declines to the degree that the person becomes liberated from its sacred obligation to the group, and the rise of moral individualism….”

“This is in accordance with a society in which ‘honour’ constitutes highly important social capital of the male person as a representative of his group…. Such a theoretical framework may help to better understand why the secular decline in homicide rates primarily seems to have been due to a decrease in male-to-male fights. And it may also offer a point of departure for understanding the high violence rates in Italy, where a culture of honour persisted despite the early development of administrative and judicial structures in the city states.” [pg. 632]

england, the netherlands, belgium, germany and switzerland saw the earliest reduction of violence because they were the european populations who started outbreeding the earliest (in some cases, as early as the 500s). the scandinavians — the swedes and the norwegians, anyway — probably didn’t start outbreeding until sometime after ca. 1000 a.d. when they converted to christianity. that could amount to nearly 500 years less outbreeding compared to the franks and the english, and their reduction in crime was a few hundred years later as well.

populations on the periphery — the irish, the spanish, the italians, the hungarians — all continued to be much more violent than “core” europe for a much longer time AND they also all kept inbreeding in one form or another longer than the germans or the english. and the italians? — differences between the north and south, again! — the south being more violent than the north.

i know, i know. i start to sound like a certain individual (won’t mention any names!) who has only one explanation for everything. i don’t think inbreeding/oubreeding and altruism explains everything. REALLY! but i do think it applies in this case. it’s not the entire explanation (i think the role of the state is important, too, for instance) — and there’s more to it than just how much inbreeding/outbreeding there is. like greying wanderer said:

“i think there’s likely to be a compounding effect too. as the clannishness recedes it becomes easier – and in fact neccessary as the only previous rule of law was clan vendetta – to institute a communal rule of law instead.”

absolutely! with all of the outbreeding, european societies became more “corporate” simply because the old extended-family/clan/tribal ties disappeared. everything had to be arranged differently. but europeans — northwestern europeans more than others — also just felt differently about the world and their place in it and their relationships with others than their ancestors had. ’cause they were different.
_____

h/t to halvorson for pointing out a post by agnostic on this paper from a couple of years ago @gnxp. thnx, halvorson!

(yes, i’ve got pinker’s new book sitting and waiting for me on my kindle. and i am planning on reading it. any day now…. (~_^) )

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I had to scrap the entire reply that I had in mind when I read your last sentence! ;) The data detailing the decline of homocide in Europe is one of the key bits of evidence in Pinker’s latest book (which I have yet to read as well).

I wonder if it dawned on Pinker that the very fact there are records from Medieval Europe going back that far, especially in England, says something about those societies?

For those who don’t have access to Nature here’s the review of Hamilton the reductionist: [hope this is legal/]

“This book is the evolutionary biologist’s Harry Potter: the long-awaited sequel to a captivating story of a young man with extraordinary powers. For W. D. “Bill” Hamilton was one of the twentieth century’s greatest evolutionary biologists. He saw the world in a profound new way and, in elucidating his vision, changed for ever the way the rest of us see the world too. His discovery of inclusive fitness — namely, that an organism can spread its genes by helping its relations to spread theirs — blasted a path for understanding the evolution of altruism, and incidentally founded the field of sociobiology. His work on the evolution of sex ratios, which predicted when sex ratios might deviate dramatically from one-to-one, pioneered the use of game theory in evolutionary biology.

With the first volume of his collected papers (Narrow Roads of Gene Land. Volume 1: Evolution of Social Behaviour, W. H. Freeman, 1996), Hamilton created a dazzling new form of scientific autobiography. Each of the 15 papers he published between 1963 and 1980 is preceded by a brief sketch of his life and thoughts at the time he was working on a given idea. Funny, erudite, compelling and often poignant, these sketches show a lonely outsider struggling to make his radical ideas heard.

By itself, the brilliance of Volume 1 would have guaranteed interest in the sequel. But there is another, sadder, factor. In March 2000, Bill Hamilton died, the autobiographical sketches for Volume 2 just completed. In a real sense, then, these sketches are his last words. Mighty strange last words they are.

No longer straight-up autobiography, the sketches in this volume are a thorny and unweeded thicket of scientific advocacy, political manifesto, broken intellectual taboos, self-revelation and apocalyptic vision. They swirl from one topic to the next so fast that sometimes the reader has the impression of being party to a phantasmagoria. Hamilton does recount plenty of entertaining stories: the “Greasy Sheet Award” for the worst hotel he ever stayed in goes to a bed and breakfast in Ireland, where not only were the sheets dirty, but the landlady’s son crept into the room in the middle of the night and slept on the floor — and there wasn’t any breakfast. Hamilton’s erudition and humour are still there, but they are mingled with anger, frustration and bitterness.

Volume 2 opens with him working in America, at the University of Michigan. By this point, his early ideas — the papers of Volume 1 — had been accepted, and he had come in from the cold. This surely made for a more conventional, even mundane, academic life. Moreover, Hamilton had, by and large, shifted his attention to the evolution of sex, a problem he grappled with until he died. The 18 scientific papers of this volume — published between 1980 and 1991 — reflect the change in both focus and lifestyle. In Volume 1, only three papers have co-authors, and virtually every paper tackles a different subject. Here, almost half have co-authors, and more than half are devoted to exploring aspects of Hamilton’s favoured explanation for the evolution of sex — this invokes antagonistic coevolutionary interactions between hosts and their harmful parasites, a theory known as the Red Queen.

It is here that the scientific advocacy comes in: as he admits in the preface, Hamilton felt (correctly) that many of the scientific ideas represented in this volume are not generally accepted, and he thus devotes considerable chunks of the sketches (as well as two appendices) to additional argument and persuasion. The anger and bitterness are also explained. Hamilton includes a citation analysis showing that one of his papers, which was twice rejected by Nature, has since been more influential than two papers on the same subject (by other authors) that Nature accepted at roughly the same time. But although the emotions he describes will be familiar to anyone who has had a cherished paper rejected, this passage amounts to an object lesson on why it is ridiculous to become exercised over losing Nature’s lottery. What is perhaps most startling about all this, however, is Hamilton’s openness about his disappointments and set-backs. In writing autobiography, most authors polish the image they present to the world and hide moments of anguish and defeat.

But the self-revelation is nowhere near as startling — or disturbing — as the mix of politics and apocalypse that suffuses the sketches. Take the politics first. Hamilton is an unabashed, no-fig-leaf naturist. He believes that genetics, not nurture, accounts for a large and important range of human behaviour — from racism and xenophobia to differences in intellectual abilities between men and women — and that only by admitting and understanding this, only by casting aside hypocrisy on the matter, can fundamental human problems be tackled. As an example, he argues that a basic cause (emphatically not a justification) of racism — and, particularly, of ethnically motivated genocide — is a differential birth rate between groups. And, yes, he does extend this to the Nazi extermination of Jews.

Much of this makes uncomfortable, even offensive, reading. But to be fair, much of the discomfort has less to do with the truth (or not) of Hamilton’s statements than with the fact that he raises possibilities that most of us shrink from contemplating. After all, it is self-evident that the human psyche has been shaped by natural selection; and it is certainly possible that the shape is an ugly one. But I feel — and this is where I completely disagree with Hamilton — that, although understanding how natural selection has acted on humans will help us to understand why we are the way we are, it tells us nothing about what we would like to become.

And the apocalypse? For the human species, Hamilton foresees an imminent mutational meltdown — the crippling accumulation of deleterious mutations — as a consequence of modern medicine. He evaluates three courses of action: do nothing (which will lead to the coming of the “planetary hospital” and certain doom), germline intervention (desirable but impractical, perhaps impossible), and a return to natural selection (salvation). Whew! Of course, this question is worth investigating. If humans have done away with natural selection — which is by no means obvious — then deleterious mutations will start to accumulate. Even so, Hamilton’s view is inconsistent in several respects. He despises efforts to keep children with genetic defects alive, and abhors the fact that caesarian sections allow women with narrow hips to give birth. However, neither of these supposed evils seems likely to contribute significantly to mutational meltdown. Moreover, he ignores other, more important sources of relaxed natural selection — such as vaccination programmes, and an adequate food supply. And as for returning to natural selection — well, more natural selection equals more death, which is hardly something to agitate for.

The full strangeness of this book cannot easily be explained away. None of the themes is new. A close reading of Volume 1 shows that all the currents — the naturism, the concern about deleterious mutations, even some of the personal bitterness — are lurking in the background. For those who knew Hamilton well, this book evokes his voice, his manner, his laughter. I cannot agree with much of the content. But perhaps it is not surprising that someone with such an original view of the natural world should also have disconcerting and discomfiting views of Homo sapiens.

Re Eisner’s charts of the decline in violence in Europe. It is hard (for me) to put these data in a context, i.e. is this a big or a small social change from 1200 to the present? The simplest way I know is to imagine that there is some underlying Gaussian propensity to violence and that murderers are on the wrong side of a threshold.

So if the murder rate is 50/100000 or .0005 at the beginning of the period, the threshold is 3.3 standard deviations away from the population mean. Selection (or something) we imagine shifts the whole distribution leaving the SD unchanged. After 800 years the threshold is at 1/100000 or 4.3 standard deviations away from the mean, so the change has been 1 standard deviation in 32 generations or 1/32 a standard deviation per generation. Not so great, like a tenth of an inch in height per generation.

Would simply removing murderers be strong enough selection? If we truncate at 3.3 SDs the mean of the parents of the next generation is -.002 about, say -.06 after 32 generations, or -.03 if the heritability is 1/2, far from the 1SD we observe.

“He believes that genetics, not nurture, accounts for a large and important range of human behaviour — from racism and xenophobia to differences in intellectual abilities between men and women — and that only by admitting and understanding this, only by casting aside hypocrisy on the matter, can fundamental human problems be tackled.“

yes, yes, yes. if you really want to fix problems in the world — and i actually believe most people do not and that most of what they say about “making the world a better place” is hypocritical, deception/self-deception stuff (pardon my cynicism) — you need to understand what causes them. otherwise there’s no hope in hades that you’ll be able to change them

if you take a fairly inbred, clannish population (the pre-christian swedes) and get them to start outbreeding, how many generations would one need to change their pattern of behavior from warring clan members to peaceable, sauna-loving saab drivers? is ca. 500 years (sometime after ca. 1100 when they finally adopted christianity to 1600 when their murder rates seem to drop off a cliff) enough? could it happen that quickly? (of course, the answer might also depend upon what the rate of outbreeding was in each generation.)

the scandinavia scenario that eisner presents seems unusual compared to england and germany because of the steep decline in the 1600-1700s, but the english and germans started outbreeding much before the scandis — in some instances as early as 500 a.d. perhaps there were steep declines in their murder rates, too, only much earlier (that are not apparent on eisner’s charts since they don’t start until 1200).

“The simplest way I know is to imagine that there is some underlying Gaussian propensity to violence and that murderers are on the wrong side of a threshold.”

I don’t think it works quite like that.

On the one hand there’s a long list of things like
– impulsiveness
– low IQ
– low empathy
– bad temper
– low alcohol tolerance
or whatever, which all together and in various doses would give you a gaussian distribution for a propensity to violence. However none of these people want to kill anyone – even among the most violent – and randomness is more a factor than anything else e.g. the subset of people who walk in on their spouse with someone else. You can have extremely violent populations e.g. soccer hooligans, who are almost entirely non-lethal.

However there’s also a very specific killer type, someone who
– gets some kind of dopamine rush from inflicting harm
– habitually carries a weapon
– doesn’t have the normal restraint when using potentially lethal violence

This type, because of their specific characteristics, have a much higher lethality. If they were 1% of a male population then they might be responsible for 2% of the violence and 4% of the killings and if they were 12% of a male population they might be responsible for 24% of the violent incidents and 48% of the killings. So there’s “normal” violence and there’s the killer types. In a justice system based on clan vendetta this trait would be a neccessary evil** but as soon as a more communal rule of law was established they’d be selected against very strongly. I think medieval Europeans had a much higher frequency of this trait and it was gradually bred out.

(** They’re killers not warriors, and can kick off at any time including among friends. The warriors are those with this trait plus some other compensating restraint that controls it.)

This ties in with US army research related to how many soldiers aim high in war (almost all of them) and how there’s only 2% or so who don’t have that mental block.

@g.w. – there was a footnote in the eisner article that i had in the post originally but i took it out ’cause it seemed like too much of a digression — the footnote was related to the stuff about the psychological profile being altered via norbert elias’ “civilizing process” (i.e. one example of what biologists call evolution by natural selection (~_^) ).

here is that footnote!:

“From a criminological perspective, the striking correspondence between this [norbert elias’] argument and the ‘general theory of crime’ as proposed by Michael Gottfredson and Travis Hirschi is worth mentioning. As is well known, their theoretical model postulates that low self-control constitutes a generalized personality trait that is ‘the individual-level cause of crime’. According to Gottfredson and Hirschi, low self-control involves a tendency to seek immediate gratification, a preference for simple tasks, a tendency toward risk-seeking behaviours, a preference for physical as opposed to mental and relfexive activities, a high level of impulsivity, and an indifference to the needs of others. They thus delineate a theoretical concept that coincides to an astonishing degree with Elias’s definition of ‘self-coercion’ as a higher degree of control over spontaneous impulses, and increased ability for long-term planning, and a higher reflexive sensitivity to inner psychological states and processes.” [pg. 619]

my first reaction would be to say no but that may be a result of distorted experience.

the thing is if you have a trait and two distinct populations: one where this trait has a high frequency and dominates the culture and one where it has a low frequency and is suppressed, then maybe it just displays so differently that it appears as two separate things?

For example, in the second population maybe it mostly only survives among people with large amounts of self-control which gives it *on the surface* a very different character even though it’s the same underneath.

In the past men could duel and settle disputes with one on one fights ending in death and fight for honor and stuff.

You can’t do that today and most homicides today seem to be impulsive or predatory and sociopathic. Gangs killing someone, killing in robbery or some other crime, serial killers or other sociopathic type homicides, etc.

it depends how far back you go maybe. i read the icelandic sagas too long ago to recall how many of the killings in that were fair fights. the only incident i remember was a “gang” setting fire to a house and then crowding round the doorway cutting down anyone trying to get out.

i wonder if maybe a lot of the more rule-based violence like duels may come about at times when the level of lethal violence in a society was coming down to a point where it could be controlled culturally.

so maybe it’s the percentage of killer types – if it’s beyond a threshold they dominate a culture and it’s all ambush and surprise attacks becoming more formal and controlled as a rule of law takes its effect and the percentage are whittled down?

@luke – “How about external state violence? How does that correlate? Is nationalism one of the glues that holds the state together? Just wondering.”

oh, boy. now you’re entering some deep waters there, and i’m not a very good swimmer! (~_^)

i really dunno. i haven’t thought any of this through all the way up to the state level yet (not really, anyway) — but i still might not have a clue even after i (try to) do that.

the only thing that i can think of right now is that there are different sorts of states, aren’t there? some are really “top down” driven (any chinese state you can think of), others have more input from the bottom (or the middle, maybe — early u.s., england), some are nation-states or as close as you can get to one (sweden? ireland? japan?), some are mix-and-match hodge-podge groupings (italy, almost all sub-saharan countries).

how and where to start contemplating all of those in relation to inbreeding/outbreeding, self-control and violence, i dunno. next year’s project maybe. (^_^)

yeah, that’s where these criminologists could use a good dose of (socio)biology. it prolly/mostly isn’t self-control in the sense of a conscious effort at controlling oneself that we’re talking about it — it’s just more of an innate way of behaving. mostly not flying off the handle at every little slight.

well, exactly. that’s what eisner is driving at, i think, when he talks about how lethal violence seems to have shifted from being a more honor-driven, guy vs. guy thing (“why the secular decline in homicide rates primarily seems to have been due to a decrease in male-to-male fights.”) to, like you say, what we have today — either an impulsive or predatory act.

the greatest reduction in the homicide rates from the medieval period to now comes from the reduction in male-to-male fights. why?

eisner suggests a “civilizing process.” i suggest that that civilzing process selected for different/different frequencies of altruism (and other behavioral-related) genes in european populations.

“it’s just more of an innate way of behaving. mostly not flying off the handle at every little slight.”

imagine punching a toddler in the face. the more empathic the person the harder it would be for them to even imagine doing it without wincing. scaled up to an argument between adults it’s weaker but still there. the average WEIRD male might be able to imagine punching another adult male in the face without wincing but ask them to imagine sticking a knife in someone’s neck and then twist it and they’d be back to wincing again.

so in a potentially violent situation two WEIRD males (or urban Asian equivalent) might almost come to blows but are restrained by the wincing i.e. identifying with the other person’s pain before it has actually happened (like people cringing in horror films just before the victim gets hurt). so they go through the decision tree, choose “no” to “use violence” because of all the various restraining mechanisms in play including empathic restraint, and then have to think of an alternative way to resolve the dispute.

“the greatest reduction in the homicide rates from the medieval period to now comes from the reduction in male-to-male fights. why?”

i think there’s a really important distinction here between willingness to use violence and willingness to use potentially lethal violence. the reduction in the homicide rate from male-to-male fights doesn’t neccessarily mean a redcution in fights – although i think it probably did as well – but a reduction in fights that ended in a death.

@harpend – “If you are not into it already, recent literature on runs of homozygosity has a lot of promise for looking not only at inbreeding but its history in various populations. For a start have a look at….”

cool! thanks!

now if we just knew which ones were the “genes for altruistic behaviors,” we’d be all set. (~_^)

If “homicide” in the past and more recent times is qualitatively different to a significant degree, then I think claims regarding change in violence have to be qualified.

One society might have more men killed by other men, but it might be all due to fair fights where both men agree to fight. While another society might have relatively fewer men killed by other men, but it might be all due to gang or state/military violence or other group violence and criminal predation, serial killer type violence. The type is quite different. The societies look quite different.

@bob – “If ‘homicide’ in the past and more recent times is qualitatively different to a significant degree, then I think claims regarding change in violence have to be qualified.

absolutely. if there is a significant difference in types of killings between different populations, then that would make a … uh … difference. (^_^) i guess that’s why eisner went for the broader, more inclusive phrase “lethal violence” — covers all sorts of killing.

it should be noted that his data sets include a variety of types of killing including, for instance, infanticide. but the interesting part is that it was the instances of male-to-male lethal violence that decreased the most.

Bob
“If “homicide” in the past and more recent times is qualitatively different to a significant degree..The type is quite different. The societies look quite different.”

it’s true that the societies are different but i’m beginning to think the quality may be decided by the quantity of killer-types.

if you have a population with a very high frequency of killer-types then it becomes too risky to fight fair as you’ll have to throw the dice too often and you’re bound to lose eventually. if so then your society gets like the Yanomani or the urban underclass where violence is all about ambush, gang-jumping and people getting stabbed or shot in the back – as low risk as possible and as lethal as possible so there’s no comeback.

a population with a medium frequency might lead to the larger non-killer proportion being able to exert some greater degree of control and possibly to the fewer killers making more of a sport out of it because as the number of opponents would be fewer they could afford to play by some rules. however i’m starting to be more inclined to the view that this level of frequency would be caused by and represent a partial rule of law where the killers had been actively squeezed a bit but were still partially neccessary. i the most violent end of this layer might be something like Njal’s saga or Border Reivers and it’s at the least violent end of this layer where you maybe get the lethal duelling – when the upper class of the society are just on the cusp of dropping lethal violence for boxing.

(this middle layer would be very broad and as it doesn’t exist in the modern west maybe that’s why the two extremes look so distinct and not part of the same spectrum?)

a population with a low frequency might be 1960s white nw euro bluecollar – lots of violence, much of it “duel-style” one-on-one – but non-lethal using fists

a population with very low frequency – white/asian whitecollar – very little male fighting at all – almost all of it ritualized into sport – which still provides a certain amount of fierceness polygyny.

at the very lowest frequencies all you need is enough of this type with other compensating traits to deal with the residual percentage – unless you import huge numbers of young men from places with a much higher frequency – in which case you just cut your own throat.

[…] northern italy and parts of france — civic societies. violence rates begin to fall in the 1200s, especially in more outbred populations, i would argue (guess!) because the impulsive violence related to clan feuding was no longer being […]

If genetics is key to this, can someone explain to me why, when the evidence adduced here seems to be entirely from European populations, the Europe-origin population of the USA is so much more sanguinary than Europeans, and Canadians of similar origin. Or am I missing something really obvious . .. !?

John Skrine,
You are missing something really obvious – mostly that even when we speak of “European populations” as little as 300 years ago it would be better to speak of specific regional areas, and at 500 years ago, the regions are larger in quantity and smaller in size.
On JayMan’s site, he has some links describing the maps of North America, and mentions other sources – one being the book Albion’s Seed – that describe the settling of America, Canada etc as separate cultural groups coming out of England (and Europe in general) and arriving in North America. The gist of it is, that as they left Europe, these groups primarily settled in with their culture in North America, and while the US and Canada formed single countries, they are really made of up of cultural and genetic sub groups.